Obama has been under pressure from some Democrats to issue a response to Russia over the hacking before he cedes the White House to Donald Trump in January. Critics fear that Trump, who has expressed a desire for warmer relations with the Kremlin, will take no action against Russia.

Some Republicans have also called for retaliation, but have argued that the response should come from the new administration.

According to the Post, the White House is still hammering out how best to adapt a 2015 executive order that gave the president the authority to levy sanctions against foreign actors who carry out cyberattacks against the U.S.

The order was used as the “stick” in negotiations over a highly publicized 2015 agreement with China that neither nation would hack the other for economic gain.

But officials concluded this past fall that the order does not cover the kind of covert influence operation that the intelligence community believes Russia carried out during the election — hacking political organizations and leaking stolen emails with the goal of influencing the outcome.

The April 2015 order allows the Treasury Department to freeze the assets of individuals or entities who used digital means to damage U.S. critical infrastructure or engage in economic espionage.

Officials told the newspaper that the order could be amended to clearly designate that it applies to election interference, or the government could declare the electoral system “critical infrastructure” — a controversial proposal that states have pushed back on in the past.

If the administration relies on the original 2015 order, it will also have to demonstrate some proof that the individuals or entities it names were involved in the scheme.

Up until now, the White House has provided little documentation to back up its official October assessment that the Russian government was attempting to “interfere” in the U.S. election.

The CIA and the FBI have reportedly assessed that the hacking and subsequent data dumps were an explicit effort to help Trump attain the White House at the behest of Russian President Vladimir Putin.